Process for producing welding powders



United States Patent M V 3,2913% PRQCESS FOR PRGDUQNG WELDING PQWDERS Gustav Miitschitzhy and Walter Schindelin, Burghausen, Upper Bavaria, Germany, assignors to Waclrer-(Jhemie G.rn.b.l-i., Munich, Bavaria, Germany, a corporation of Germany No Drawing. Filed Mar. 2%), 1962, der. No. 181,154 Claims priority, application Germany, Mar. 30, 1961, W 29,736/61; tan. 23, 1962, W 31,526/62 13 Claims. (6!. 1148-26) This invention relates to the manufacture of welding powders and it has for its object to provide a novel and improved process for this purpose.

Another object of the invention is to provide composite welding powders which contain the essential ingredients of known basic welding powders but have lighter powder densities than said known powders and insure more effective welds than heretofore.

Still another object is to provide composite welding powders in which the individual particles or granules are composed of a core of foamed basic welding substances enveloped in a coating which contains oxidizing and/ or deoxidizing agents and materially increases the effectiveness of the weld.

Various other objects and advantages will become apparent as the nature of the invention is more fully disclosed.

Loose free-flowing welding powders with the customary powder densities (kg/liter) are partly melted during Welding by the arc. The slag settles on the fluid material and thus it forms the welding seam. During the welding process masses of welding powder are introduced into the liquid slage bath by their own weight and thereby they didilh-z Patented Aug. 17, 1965 As additives we can, for instance, use metals which combine with nitrogen and thus increase the impact resist ance or toughness, such as vanadium, niobium, tantalum.

Boron, which has hardening properties, can also be added,

By the addition of tungsten the metal itself can be hardened, while by the addition of chromium or molybdenum the weld can be made tough-hard. The addition of zirconium and titanium imparts a fine-grained texture. Generally all additives can be used that improve the welding seam or which bring it into conformity with the com-.

position of the base material.

The enveloping or covering substances which lend the basic properties to the welding powder are the same as those that usually give welding powders their basic character. These are for instance oxides, carbonates, aluminates, titanates or basic silicates of the metals of the 1st and 2nd main groups of the Periodic System or of the rare earths singly or in mixtures, in suitable cases adding fiuorspar or cryolite.

If the welding powder is to be useful for rapid welding processes, it is advantageous that it have a mild oxidizing eifect. For this purpose one uses enveloping components containing oxidizing agents in fine form, for instance oxides of manganese or of iron.

In order to prevent the burning out of alloy components of the basic working material and the introduction of oxides, deoxidizing agents are added to the enveloping mass, as for instance ferro-silicon, calcium-silicon, aluminum-calcium-silicon, aluminum-silicon, magilesiun'i-calcium-silicon, manganese silicide, chromium silicide.

. However, it is also possible to combine the envelopers in such a way that welding powders are obtained which for instance have a basic and oxidizing or a basic and cool the bath. In this way the slag bath remains toughly the processing of rusting sheet iron, gases are'formed from" the iron oxide and the moisture which is present.

Attempts have been made to eliminate the above defects by using welding powders with light powder densities. These float on the liquid slag, and, since their own weight is small, they cannot penetrate into the slag bath so much and they cool it very little. Due to the higher heating a thinly liquid slag layer is formed which passes gases easily. This reduces the multitude of pores in the seam which is formed.

Furthermore, due to the small powder density the welding seams which are formed show a smoother, more flatly arched and wider surface than the welding seams made with welding powders of customary powder densities.

Since it is not possible to have all melting substances foam well, particularly the basic ones employed in welding powders and those containing many heavy metal oxides, it has heretoforebeen impossible to make Welding powders of the kind mentioned with lower powder den--- sities.

This deficiency has now been overcome by ourj.

present invention according to which acid or neutral basic substances which have been foamed and granulated by 9 any suitable method are covered or enveloped by a coating of basic components and/orcomponents containing-- oxidizing and/or deoxidizing agents.

For acid or neutral basic substances, preferably fused by weight.

deoxidizingeifect. V V

Furthermore, materials can be added to the enveloping mass that improve the welding seam and are notcontained in the foamed base substance. lFor: this purpose metals, metal alloys, metal oxides of the 4-8 sidegroups of the Periodic System may usually be employed singly or in mixtures. Thereby it is possible also to bind the nitrogen for instance and to increase the notched-bar toughness or to change the hardening properties or to make the texture fine-grained.

To make the welding powders one mixes for example soda. The base substance, thus treated, is mixed with 7 EXAMPLE 1 Base materials with the compositions shown in Table I are melted in the electric furnace and foamed by pouring the melt into water.

. n on U 1.? Table I furnace to about 900 C. for one hour. After cooling the enveloping substance which has not been sintered is Base Materials separated from the finxshed weldmg powder by screening.

Ingred r Table III [Weldmg powder eombinatwn accordmg to Example 1] S102 38. 27 Fea 0. 15 Envelop. mat. Powder A1z03 12' 2 Base mat. Powder Percent. Density TiO No. Density of Weld. M110- 6, 09 10 No. Percent. Powder 050... 10.01 MgO 11.20 051% 8. 05 0. 542 75. a 24. 75 0. 703 V 0 go 0. 542 71. 50 c 28. 50 0. 788 FeCr 0. 798 86. 50 a 13. 50 0. 747 Fe'li 0. 793 84. b 15. 00 0. 780 Fe 0. 798 88.70 c 11.30 0.002 Powder density"... 0. 542 0.875 04753 77-40 6 0.798 0. 708 83.30 (1 10. 0. 922 0. 70s 68. 24 g 31. 70 0. 977 After drying, the pieces of .foam are cut 11p into small 333% 2232 8: pieces on a roller and by tslftlng a granu1at1on of 0.3-1.5 8.738 go 1: 5 23.32 mm. is obtained. The granules which are too big are 0:822 38 24:70 0:833 cut up once more and sifted, and the particles that are 0.991 81.05 c 18.95 0.973 n f db kt th f 0.875 78.21 e 21.79 0.882 00 Sma e 0 P 0. 822 72. 42 1 27.58 0. 836 The materials enumerated 1n Table II are used for en- 0-798 76-12 1 8 0-825 vel-oping substances in connection with Example 1.

Table II Enveloping Materials Ingred a b c d e f g h 1 k 1 The base materials shown in Table I are mixed in a EXAMPLE 2 InlXlng drum Wlth the envelflplng shown In The base materials listed in Example 1, and the en- Table II and thereafter the m1xture 1s heated in a muffle Vgloping materials f the following Table IV, are used.

Table IV Ingred. a b c d e f g h 1 The base substance is sprayed with a solution of soda or silicate of soda (Na O SiO so that their percentage in relation to the total quantity of welding powder amounts to 26% dry mass. The moistened base substance is rotated in a mixing drum with the finely powdered enveloper substance until the enveloper substance evenly covers the granules of the base substance. This will have been achieved as soon as no fine particle is any longer loose in the mass. The granulated product thus 6. Process according to claim 5, in which said adhesive substance is selected from the group consisting of soda and silicate of soda.

7. Process according to claim 5, in which the envelopecoated granules are dried at a temperature of 500- 600 C.

8. A welding powder consisting of toam-like granules which are coated with an outer envelope, said granules consisting essentially of the following basic welding subob-tained is dried in a mufile or drum furnace at a tem- 10 stances in the following proportions by weight: 30-55% perature of 500600 C.

S102, 1l5% A1 0 up to TiO 1-35% CaO,

Table V [Welding powder combination according to Example 2] Adhesive Envel. mat.

Powder Base mat. Powder Percent Density No. Density Percent of Weld Kind Dry N 0. Percent Pow Subs.

0. 542 78. 48 5.82 a 15. 7O 0. 548 0. 788 80. 53 3. 37 a 16. 10 (l. 790 0. 798 79. 54 4. 55 b 15. 91 0. 718 0.798 57. 88 3. 53 c 38. 59 0. 895 0. 788 77. 70 4. 42 (l 17. 88 0. 812 0. 788 82.85 4. 49 e 12. 66 0. S34 0. 788 80. 00 4. 12 b 15. 88 0. 852 0. 798 75. 86 4. 60 g 19. 54 0. 893 0. 798 72. 60 3. 65 ll 23. 75 0. 877 0. 822 71. 00 4. 50 i 24. 50 0. 902

The invention claimed as: 05-25% MgO, up to 10% Cal-" up to 10% MnO, up to 1. Process for producing welding powders with small powder densities (kg/liter) from known basic Welding materials which have customary higher powder densities and which consist essentially of the following substances in the following proportions by weight: 30-55% SiO l-15% A1 0 11p to 15% TiO 1- CaO, 05-25% MgO, up to 10% Ca F up to 10% MnO, up to 2% Fe O which comprises compounding said basic welding material in the form of foam-like granules, and then coating said granules with an outer envelope consisting of the foregoing substances in the foregoing proportions.

2. Process according to claim 1, in which said foamlike granules are formed by melting said basic welding materials, then pouring the melt into water to cause same to foam, and then drying the foamed material and comrninuting same.

3. Process according to claim 1, in which said foamlike granules are adhesively united with said outer envelope.

4. Process according to claim 3, in which said welding powder, consisting of said foam-like granules adhesively coated with said outer envelope, are heated until slightly softened.

5. Process according to claim 3, in which said foamlike granules are first coated with a thin layer of an adhesive substance, and in which the adhesive-coated granules are then thoroughly mixed with finely-ground envelope material, 7

2% Fe O and said outer envelope consisting of the foregoing substances in the foregoing proportions.

9. A welding powder according to claim 8, in which the outer envelope consists of finely ground particles adhesively united with said foam-like granules.

10. Process according to claim 1, in which said outer envelope contains an oxidizing agent.

.11. Process according to claim 1, in which said outer envelope contains a \deoxidizing agent.

12. A Welding powder according to claim 8, in which said outer envelope contains an oxidizing agent.

13. A welding powder according to claim 8, in which said outer envelope contains a deoxidizing agent.

References Cited by the Examiner UNITED STATES PATENTS 2,443,103 6/48 Galla-i-Hatchard 1847. 2 2,474,787 6/49 Landis et al. 14826 2,662,840 12/53 Shilling et a1. 148-26 2,720,473 10/ 55 Donahey 148-26 3,023,183 2/6'2 Lewis et a1. 148-26 FOREIGN PATENTS 524,020 4/56 Canada.

DAVID L. RECK, Primary Examiner.

WINSTON A. DOUGLAS, Examiner. 

1. PROCESS FOR PRODUCING WELDING POWDERS WITH SMALL POWDER DENSITIES (KG./LITER) FROM KNOWN BASIC WELDING MATERIALS WHICH HAVE CUSTOMARY HIGHER POWDER DENSITIES AND WHICH CONSIST ESSENTIALLY OF THE FOLLOWING SUBSTANCES IN THE FOLLOWING PROPORTIONS BY WEIGHT: 30-55% SIO2, 1-15% AL2O3, UP TO 15% TIO2, 1-35% CAO, 0.5-25% MGO, UP TO 10% CAF2, UP TO 10% MNO, UP 2% FE2O3; WHICH COMPRISES COMPOUNDING SAID BASIC WELDING MATERIAL IN THE FORM OF FOAM-LIKE GRANULES, AND THEN COATING SAID GRANULES WITH AN OUTER ENVELOPE CONSISTING OF THE FOREGOING SUBSTANCES IN THE FOREGOING PROPORTIONS. 